AQA GCSE 2012 BIOLOGY UNIT 1 REVISION NOTES

Amar Patel HGS Biology Revision: How do humans' bodies respond to changes inside them and to their environment? Explain what a stimulus is by highlighting examples and what organs they stimulate. Describe how a nervous response is brought about by stimuli, including the roles of receptors, sensory neurones, the coordinator and motor neurones. Stimulus (Light bulb) -> Receptor (Eye) -> impulse travels along the sensory neurone to -> Coordinator (Brain) -> impulse travels along the motor neurone to -> Effector (Eye muscle) -> Response Neurone = A single nerve Describe a reflex action and the role of the relay neurone in this action. Receptor (Finger) -> impulse travels along sensory neurone -> comes to synapse -> goes onto the relay neurone -> to synapse -> along the motor neurone -> Effector (Arm muscle) Synapse = gaps between the end of a neurone and the start of another or an effector. Axon = the end of a neurone. Explain that four internal conditions controlled by the body include; water content, ion content, body temperature and blood sugar. Describe, in very broad outline, how they are controlled. Ion content leaves body 1) in sweat 2) excess lost via kidneys in urine. The water content of body leaves body 1) in breath 2) as sweat 3) excess is lost via kidneys in urine. Temperature -> maintain temperature at which enzymes work best. Blood sugar levels -> to provide the cells with a constant supply of energy. Describe hormones as chemicals which coordinate reactions in the body and that are secreted by glands and reach their target organs via the blood stream. Pituitary glands -> FSH and LH. Ovaries -> oestrogen and progesterone. FSH (Follicle stimulating hormone) ­ egg mature + oestrogen to be released. Oestrogen ­ thickens uterus lining + inhibits FSH LH (Luteinizing hormone) ­ egg is released from ovary + stimulates progesterone. Describe how hormones control both the monthly release of an egg and the varying thickness of the lining. Recall the location of the pituitary gland and the ovaries and that they are the main hormone glands for the release of the menstrual cycle hormones. 1 Biology Revision (Year 10) 2012

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Amar Patel HGS Describe the dual role of FSH, secreted by the pituitary, of causing eggs to mature in ovaries and to stimulate the production of oestrogen from the ovaries. Describe the dual role of oestrogen of inhibiting further FSH production and of stimulating the pituitary to produce LH. Explain how oral contraceptives work by containing hormones that inhibit FSH production. Explain how FSH can be used as a fertility drug.…read more

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Amar Patel HGS Recall that too much slat in the diet can lead to increased blood pressure for about 30% of the population. Understand that processed food often contains a high proportion of fat and/or salt.CHD ­ Coronary Heart DiseaseCVD ­ Cardiovascular Disease CHD is just the diseases to the heart and CVD is veins/arteries problems, which causes other diseases. Metabolic Rate: This is the rate at which all the chemical reactions in the cells of the body are carried out.…read more

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Amar Patel HGS o Extensive Clinical trials in various stages (side effects). [5 years] o Drug licensed for sale, if safe and effective. Tolerance ­ this is where the body gets used to the drug and more has to be taken to get the same effect. Addiction ­ this is where the person becomes very dependent on the drug and they can't go without it. Withdrawal Symptoms ­ this is when a person sops taking the drug because they have become addicted to it.…read more

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Amar Patel HGS 1990 Until as late as 1997 some people in tobacco companies disputed the link. At this point s they were forced to accept evidence as they were sued by 40 US states to pay for treatment costs. 2000 It is now an accepted fact that smoking increases risk of lung cancer. The number of s smokers in England has now fallen (80% of men smoked in 1950 compared to 30% now)continued ...…read more